1. Field of the Invention
The present invention relates to a calender roll cleaning apparatus for smoothing a surface of a magnetic layer of a magnetic recording medium.
2. Description of the Related Art
During production of a magnetic recording medium, after coating a magnetic coating material on a non-magnetic support, a calender apparatus for smoothing a surface of a magnetic layer is used. The calender apparatus includes a plurality of calender rolls, that is, metal rolls and elastic rolls, alternately disposed. After placing the side of the magnetic layer of the magnetic recording medium next to the metal roll, the magnetic recording medium is fed into a nip portion located between the metal roll and the elastic roll, whereby the surface of the magnetic layer is smoothened.
However, in the calender apparatus, a binder, a hardening agent and a lubricant of the magnetic coating material coated on the magnetic recording medium are released, whereby the surfaces of the metal rolls or the elastic rolls are stained. Also, the stains on the surfaces of rolls are transferred onto the magnetic layer, etc. of the magnetic recording medium, thereby causing drop-out of the magnetic recording medium and spoiling the recording and reproducing qualities.
In order to remove the stains from the surfaces of the metal rolls of the calender apparatus, there has hitherto been proposed a roll cleaning apparatus that brings a cleaning tape into sliding contact with the surfaces of the metal rolls.
However, in this conventional roll cleaning apparatus, the cleaning tape is brought into sliding contact with the surfaces of the metal rolls in a dry system, and therefore, the stains on the roller surfaces cannot be adequately removed. As a result, production is interrupted every hour or two, and the stains on the surfaces of the metal rolls are wiped off by hand, resulting in poor productivity.
It is an object of the present invention to adequately remove the stains from the surfaces of the calender rolls and improve productivity of the calender treatment.
A first aspect of the present invention relates to a calender roll cleaning apparatus for smoothing a surface of a magnetic layer of a magnetic recording medium passed through a plurality of calender rolls. The cleaning apparatus comprises a wiping cloth feeding apparatus that feeds a calender roll surface wiping cloth at a definite rate and tension. A cleaning liquid supplying apparatus supplies a controlled amount of cleaning liquid such that the cleaning liquid permeates into the wiping cloth fed from the wiping cloth feeding apparatus. A wiping cloth pressing apparatus presses the permeated wiping cloth at a controlled pressing load.
Incidentally, the term xe2x80x9cdefinitexe2x80x9d of xe2x80x9cdefinite tensionxe2x80x9d and xe2x80x9cdefinite feeding ratexe2x80x9d means a tension and a feeding rate, respectively, generated under a mechanically definite control. For example, not only does xe2x80x9cdefinite feeding ratexe2x80x9d include the case of setting the feeding rate to a definite rate of 10 cm/minute but also the case of varying the feeding rate by from 5 to 15 cm/minute by control rollers. The same logic is also applicable to the xe2x80x9cdefinite tension.xe2x80x9d
A second aspect of the present invention relates to the calender roll cleaning apparatus according to the first aspect, wherein the cleaning liquid supplying apparatus is equipped with a porous member that oozes the cleaning liquid and is brought into contact with the wiping cloth.
A third aspect of the present invention relates to a calender roll cleaning apparatus according to the first or the second aspect, wherein the cleaning liquid supplying apparatus controls the cleaning liquid supply amount to the amount at which the cleaning liquid applied to the calender roll from the wiping cloth is vaporized before reaching a magnetic recording medium nip portion located between the rolls.
Still another aspect of the present invention relates to a calender roll cleaning apparatus according to any aspects above, wherein the feeding rate of the wiping cloth is from 3 to 60 cm/minute and the pressing load is from 5 to 7 kgf.
According the first aspect of the present invention, the following advantageous effects are obtained. The use of a fresh wiping cloth fed at a proper feeding rate from the wiping cloth feeding apparatus. The use of a wet wiping cloth permeated with a cleaning liquid is supplied at a proper amount controlled by the cleaning liquid supply apparatus. The use of a wiping cloth pressed against the calender rolls at a proper pressing load controlled by the wiping cloth pressing apparatus so as to adequately remove stains from the surfaces of the calender rolls.
According to the second aspect of the present invention, the following advantages are obtained. The cleaning liquid supply apparatus is equipped with a porous member that oozes a cleaning liquid. By contacting the porous member with the wiping cloth, the cleaning liquid is uniformly distributed throughout the entire wiping cloth, whereby the stains on the surfaces of the calender rolls are adequately removed.
According to the third aspect of the present invention, the following advantages are obtained. The cleaning liquid supply apparatus controls the cleaning liquid supply amount to the amount at which the cleaning liquid applied to the calender rolls from the wiping cloth is vaporized before reaching the magnetic recording medium nip portion of the rolls. Thus, the cleaning liquid applied to the calender rolls disappears immediately after acting to remove the stains from the surfaces of the calender rolls, whereby the cleaning liquid is not brought into contact with a magnetic recording medium in the nip portion of the calender rolls to dissolve the magnetic coating material coated thereon.